Multiple alarm device



Aug. 2, 1966 R. H. VOlGT ETAL MULTIPLE ALARM DEVICE Filed Feb. 5, 1964 INVENTOR. ROBERT H. VOIGT JACK D. OSBORNE ATTORNEYS United States Patent poration of Michigan Filed Feb. 3, 1964, Ser. No. 342,102 13 Claims. (Cl. 340-220) The present invention relates to electrical control circuits for producing a plurality of audibly distinguishable alarms, particularly to a multiple purpose alarm device which may be activated from a remote point to warn of impending danger, such as the receiving component of the National Emergency Alarm Repeater (NEAR) system or which may be activated by the presence of smoke in the immediate vicinity of the device, and which will also produce an audibly distinguishable alarm in the event of fire within the immediate or general vicinity of the device and more particularly to such an alarm device incorporating a solid state device for its major control function.

The National Emergency Alarm Repeater (NEAR) system has been developed by the Office of Civil and Defense Mobilization to provide for use of existing power lines to provide a means of warning the population in the event of enemy attack. Generating equipment will transmit a signal in the form of a short burst of 210 or 270 cycles per second frequency superimposed on the 60-cycle power normally transmitted through the power lines. A receiver unit which is plugged into an ordinary wall receptacle will actuate a buzzer or bell upon receipt of the signal of sufiicient duration. The term NEAR voltage has been used to designate this actuation signal and will be so used hereafter.

Certain safeguards must be built into the receiving component of the NEAR system to prevent false alarms. Means must therefore be provided for delaying the sounding of the alarm for 10 to 25 seconds after receipt of the NEAR voltage, to prevent false alarms that could be caused by short accidental bursts of the NEAR voltage imposed on the lines by lightning, switching transients, etc. Also to prevent false alarms the time delay means cannot be cumulative to a series of such short accidental bursts of 2 to 5 seconds duration each. The time delay means must be independent of power line voltage, ambient temperature, humidity, and NEAR voltage ampliture, within the to 25-second tolerance specified.

A copending application, Serial No. 179,058, filed March 12, 1962, now Patent No. 3,148,365 discloses a receiver unit for the NEAR system which is provided with means for producing an alarm signal in the event of a fire which is readily distinguishable from the base NEAR alarm signal. No means are provided in this device for sounding an alarm in the presence of smoke. Further, the receiver unit incorporates a time delay means which utilizes an expandable fluid cell normally held in a closed position by a spring loaded solenoid. While such a receiver meets most of the necessary requirements, several disadvantages have been discovered with respect to this receiver. First, an audible click is sounded each time a NEAR voltage of sufficient amplitude is received. Secondly, the solenoid is subject to wear since it will respond to the presence of NEAR voltage even if the duration of the NEAR voltage is not sufficient to result in an alarm.

Another copending application, Serial No. 337,444, filed January 13, 1964, discloses an improved receiving component for the NEAR system which incorporates a solid state or transistor timing device and 'having means which will also produce an alarm signal in the event of fire or smoke.

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The present invention is similar to the device of the last mentioned copending application but provides considerable improvement over the previous disclosed device by substantially reducing the number of necessary components. This reduction in components produces economies in production as well as reliability in operation.

It is an object then of the present invention toreduce the cost of producing multipurpose alarm devices by providing a circuitry for such devices utilizing a minimum of components.

It is another object of the present invention to increase the reliability of combination fire alarm NEAR receivers by providing circuitry for such devices utilizing a minimum of components.

It is another object of the present invention to increase the reliability of combination fire alarm NEAR receivers by providing circuitry for such devices utilizing a minimum of components and isolating the fire and smoke detecting portions of the device from the NEAR signal detecting portions of the device.

It is another object of the present invention to improve combination fire alarms and NEAR receivers by providing an alarm circuit including electronic switching means and means operable upon being energized to actuate the switching means.

Still further objects and advantages will readily occur to one skilled in the art to which the invention pertains upon reference to the drawing forming a part hereof and in which the circuitry of the present invention is illustrated diagrammatically.

Now referring to the drawing for a more detailed description of the present invention, a preferred alarm device is illustrated diagrammatically as comprising a power line input plug, generally designated at 10, adapted for insertion into an ordinary A.C. wall receptacle (not shown) and having plug prongs 12 and 13 which are preferably connected to power lines 1415 as shown. A neon lamp 16 and a current limiting resistor 18 are connected across the power lines 14-15 to indicate Whether or not s-ufiicient line voltage is present to operate the device.

A resonant circuit, generally designated at 20, is connected across the power lines 14-15 and preferably includes a capacitor 21 and an inductor 22. A mechanical resonant reed member 23 and a fixed contact 24 are disposed within the magnetic field of the inductor 22 to form a discharge switch across a first capacitor 27. The first capacitor 27 is connected across lines 1415 and is charged from a rectifying diode 25 provided in the line 14 and through a resistor 26. A second capacitor 30 is also charged from the rectifying diode 25 through the resistor 26 and a blocking diode 34.

A discharge path for the capacitor 30 is provided through a resistor 36 and a neon lamp 38. A normally open thermostatic switch 40 and a series connected capacitor 42 shunt the neon lamp 38.

A photoconductive cell 44 is connected across lines 1445 and is positioned to receive light energy emitted by'the neon lamp 38. The cell 40 is series connected with the rectifying diode 25 through a resistor 46 and a variable resistor 48.

Zener diodes 50 and 52 are parallel connected across lines 1415 through the resistors 26 and 46 respectively.

An alarm circuit is connected across lines 14-15 to receive A.C. current and comprises series connected electromagnetic coil 54 and anode 56 and cathode 58 of a silicon controlled rectifier 60. The gate 62 of the silicon controlled rectifier 60 is connected to one terminal of the photoconductive cell 44. A clapper armature 64 is disposed within the magnetic field of the coil 54 and is posi- 9 tioned to strike the box (not shown) of the device upon energization of the coil 54 to sound an audible alarm.

I The resonant reed circuit 20 comprises the NEAR- signal detecting portion of thedevice. The capacitorZI: and inductor 22 form a series tuned electrical resonance circuit (L-C circuit). The capacitive reactance (X of the capacitor 21 is substantially the same as the inductive reactance (X of the inductor 22 at the predetermined NEAR signal frequency; thus upon receipt of the NEAR voltage, the two reactances cancel one another,-being 180 (degrees) out of phase, and the maximum NEAR resonate. with sufiicient amplitude to engage the fixed,

contact 24, instantly discharging the first capacitor 27.

With the capacitor 27 discharged the source of voltage to the neon lamp 38 is removed and when the Voltage level across the lamp 38 falls below its ionization level, the lamp 38 will extinguish.

With the lamp 3 8 extinguished light energy will no longer strike the photoconductive cell 44. The photoconductive cell 44- is preferably a cadmium sulfide or cadmium 'selenide cell. The resistance of the cell 44 is inversely related to the amount of light striking its sensitive portion so that as the lamp 38 is extinguished,.the resistance of the cell 44 is increased thereby increasing the voltage potential across the gate-cathode (62 and 58) circuit of the silicon controlled rectifier 60 sufficient to produce a state of conduction between the anode 56 and cathode 33 of the rectifier 60.- a

With the silicon controlled rectifier 60 in a state of conduction and acting as a half Wave rectifier, the alarm circuit will be energized and energization of the coil 54 will cause the armature clapper 64 to strike the 'box (not shown) of the device to sound an audible alarm. This alarm will continue as long as NEAR voltage is present across the power lines 14-15.-

Zener diode 52 and resistor 46 provide regulation of voltage so that the gate control voltage of the silicon controlled rectifier 60 is stable under varying line voltage conditions. Zener diode 50 is used in conjunction with resistor 26 to provide voltage regulation to the neonlamp38.

The capacitor 30 and resistor 36 provide the necessary time delay means for the NEAR receiver portion of the present invention. After the capacitor 27 is-discharged upon receipt of the device of NEAR voltage, the lamp 38 will remain energized for a predetermined time interval due to the stored energy in capacitor 30. Blocking diode 34 prevents discharge of the capacitor 30:

through the contact members 23-24.

In the event of the presence, of smoke particles of. a predetermined density between the lamp 38 and the cell 44, a sufiicient reduction of light energy striking the cell 44 will occur to cause the resistance of cell 44 to increase to a point where the voltage potential between the gate 62 and cathode 58 is increased sufiiciently to cause the silicon controlled rectifier 60 to conduct and produce an alarm identical with the NEAR alarm described above.

The thermostatic switch 40 is normally open and is preferably of a bimetal construction so that in the event of a predetermined temperature occurring within the vicinity of the switch 40 it will warp to a closed position.

first means includes a time delay means activated upon.

With the switch 40 closed, the voltage potential across 40, it no longerMconducts and the capacitor 42 begins; charging. When the capacitor 42 has charged sufiicientv to increase the vvoltage potential across the lamp .338 to the ionization level, the lamp 38 will again light to inter rupt the alarm. Thelamp ;38 will remain lit' only a short time because conduction through the lamp 38 will produce a discharge tromthe capacitor 42 which will again reduce the voltage'potential to a pointbelow the ioniza-- tion level of the: lamp '38.: This cycle-will repeat until" the switchi40 opens through a reduction of; temperature to a safe point. a

It is apparent that the .present invention provides a multiple purpose alarm in whichthe number of com-:

ponents'hasbeen reduced to a minimum; This reduction in components has beenachieved without sacrificing reliability of the device;

It is also apparent that although' we havedescribed actuation signal thereon, amultiple alarm;device com-- prising (a) analarm circuit in'cludinga switching means and means producing an alarm uponapredetermined voltage potential being impressed across said switching means,

(b) a control circuit including a light responsive'means connected with said switching .means and operable to increase the voltage potential across said switch-- ing means to said predetermined value .upon the light energy received by said lightresponsive means decreasing to a predetermined value, 1

(c) said control circuit further comprising a light emitting meansacloselyadja'cent saidlight responsive means and :a first. means de-energizing said light? emitting means upon receipt of saidpredetermined actuation signal, and a seoondmeans de-energizing saidlight emitting means upon the temperature in the vicinity of said second means increasing to a predetermined value.

2. The device as defined in claim 1 and in which said second means includes means intermittently reenergizingv said light emitting means duringv said predetermin'ed' temperature increase whereby the alarm sounded thereby is interrupted.-

3. The device as defined iniclaim l and in which said receipt ofsaid predetermined actuation signal and being operable to delay de-energization of said light emitting means for a predetermined time interval.

4. The device, as defined in claim? and in which said time delay means comprises,

(a) a capacitor. parallel connected .with --said light emitting means, and

(b) means discharging said capacitor across said light emitting means at apredetermined rate uponsaid time delay means being activatedvwhereby said light emitting means remains energized. for av predeterv mined time interval upon activation-of said time delay means.

5. The device as defined in claim 1 andin which conductive cell, (b) said light emitting means. comprises a neon lamp,

-and

voltage to said lamp during energization thereof;

6. In analarm circuit havinga source of electrical:

power and means selectively imposing a predetermined actuation signal thereon, a multiple alarm device comprising (a) said light responsive means comprises a photo-- (0) including means operable to supply a constant.

(a) an alarm circuit including a switching means and means producing an alarm upon actuation of said switching means,

(b) a control circuit for actuating said switching means including a light responsive means connected with said switching means and operable to actuate same upon the light energy received by said light responsive means decreasing to a predetermined value,

(c) said control circuit further comprising a light emitting means closely adjacent said light responsive means and a first means de-energizing said light emitting means upon receipt of said predetermined actuation signal and a second means de-energizing said light emitting means upon the temperature in the vicinity of said second means increasing to a predetermined value.

7. The device as defined in claim 6 and in which said second means comprises a normally open temperature responsive switch shunting said light emitting means.

8. The device as defined in claim 7 and in which said second means includes means intermittently re-energizing said light emitting means during closure of said temperature responsive switch whereby the alarm sounded during closure of said switch is an interrupted alarm.

9. The device as defined in claim 8 and in which said last mentioned means comprises a capacitor series connected with said temperature responsive switch.

10. The device as defined in claim 6 and in which said first means includes a time delay means operable to delay de-energization of said light emitting means for a predetermined time interval upon receipt of said predetermined actuation signal.

11. The device as defined in claim 6 and in which said first means comprises,

(a) a capacitor shunting said light emitting means,

and

(b) means discharging said capacitor upon receipt of said predetermined actuation signal, and

(c) means directing the discharge of said capacitor across said light emitting means whereby said light emitting means remains energized for a predetermined time interval upon receipt of said predetermined actuation signal.

12. The device as defined in claim 11 and in which said discharging means comprises (a) a resonant circuit including an inductor,

(b) a normally open discharge switch shunting said capacitor and operable to be closed by said inductor only when said predetermined actuation signal is imposed upon said resonant circuit.

13. The device as defined in claim 12 and in which said directing means includes a blocking diode disposed between said discharge switch and said capacitor.

No references cited.

NEIL C. READ, Primary Examiner.

R. ANGUS, Assistant Examiner. 

1. IN AN ALARM CIRCUIT HAVING A SOURCE OF ELECTRICAL POWER AND MEANS SELECTIVELY IMPOSING A PREDETERMINED ACTUATION SIGNAL THEREON, A MULTIPLE ALARM DEVICE COMPRISING (A) AN ALARM CIRCUIT INCLUDING A SWITCHING MEANS AND MEANS PRODUCING AN ALARM UPON A PREDETERMINED VOLTAGE POTENTIAL BEING IMPRESSED ACROSS SAID SWITCHING MEANS, (B) A CONTROL CIRCUIT INCLUDING A LIGHT RESPONSIVE MEANS CONNECTED WITH SAID SWITCHING MEANS AND OPERABLE TO INCREASE THE VOLTAGE POTENTIAL ACROSS SAID SWITCHING MEANS TO SAID PREDETERMINED VALUE UPON THE LIGHT ENERGY RECEIVED BY SAID LIGHT RESPONSIVE MEANS DECREASING TO A PREDETERMINED VALUE, (C) SAID CONTROL CIRCUIT FURTHER COMPRISING A LIGHT EMITTING MEANS CLOSELY ADJACENT AND LIGHT RESPONSIVE MEANS AND A FIRST MEANS DE-ENERGIZING SAID LIGHT EMITTING MEANS UPON RECEIPT OF SAID PREDETERMINED ACTUATION SIGNAL AND A SECOND MEANS DE-ENERGIZING SAID LIGHT EMITTING MEANS UPON THE TEMPERATURE IN THE VICINITY OF SAID SECOND MEANS INCREASING TO A PREDETERMINED VALUE. 